Thirty-nine extracts obtained from flower heads of 13 Achillea species [A. multifida (DC.) Boiss., A teretifolia Waldst.&Kitt., A. schischkinii Sosn., A. setacea Waldst.&Kitt., A. crithmifolia Waldst.&Kitt., A. falcata L., A. biebersteinii Afan, A. coarctata Poir., A. millefolium L. subsp. pannonica (Scheele) Hayek., A. clypeolata Sm., A. kotschyi Boiss. subsp. kotschyi, A. phyrigia Boiss.&Bal,. and A. nobilis L. subsp. neilreichii (Kerner) Formanek] were evaluated for antimicrobial activity against Escherichia coli ATCC 29908, hemorrhagic E coli (O157:H7) RSSK 232, E. coli ATCC 25922, Staphylococcus aureus ATCC 43300 (methicillin/oxacillin-resistant), S. aureus ATCC 6538/P, Streptococcus epidermidis ATCC 12228, Salmonella typhimurium CCM 5445, Bacillus cereus ATCC 7064, Bacillus subtilis ATCC 6633, Pseudomonas aeroginosa ATCC 27853, Enterococcus faecalis ATCC 29212, and Candida albicans ATCC 90028. The minimum inhibitory concentrations (MICs) were determined for all extracts against the tested organisms. Hexane extracts of A. coarctata and A. setacea showed antibacterial activity against L faecalis (MIC=31.25 and 62.5 mu g/mL, respectively). Chloroform extracts of a number of Achillea species showed selective activity against the tested bacteria isolates; MICs for the most active species (A. teretifolia, A. multifida) were found to range from 50 to 75 mu g/mL against S. aureus, S. epidermidis, and S. typhymurium. All of the extracts were inactive against C. albicans at the tested concentrations. The study has shown that several Achillea species possess antibacterial activity, which may yield novel antibacterial compounds with potential use as phytotherapeutics.